Estimation method for residual discharging time of batteries

Abstract

An estimation method for residual discharging time of batteries includes the steps of: providing a set of battery-discharge-current intervals and a set of battery-discharge equations, setting the discharge time of each battery-discharge-current intervals at zero; detecting a discharge current, voltage and time of batteries; judging whether the discharge current exceeds all of the battery-discharge-current intervals; selecting one of the battery-discharge-current intervals and the associated battery-discharge equation according to the detected discharge current; calculating an estimation of residual discharging time; accumulating and recording the discharge time; judging whether the discharge voltage is lower than a predetermined value and calculating an estimation error of the residual discharging time; and adjusting parameters of the battery-discharge equation for reducing the estimation error of the residual discharging time if the estimation error is greater than a predetermined error value.

What is claimed is: 
     
       1. An estimation method for a residual discharging time of batteries, comprising the steps of:
 A. setting a series of battery-discharge-current intervals for a discharge procedure from a discharge start step to a discharge terminating step and multiple separate battery-discharge equations thereof, with each of the multiple separate battery-discharge equations corresponding to at least one of the series of battery-discharge-current intervals, and further setting a discharge time of each of the series of battery-discharge-current intervals at zero; 
 B. detecting a discharge current, a discharge time and a discharge voltage of the batteries; 
 C. judging whether the discharge current exceeds all of the series of battery-discharge-current intervals, and terminating if the discharge current exceeds all of the series of battery-discharge-current intervals; 
 D. selecting one of the multiple separate battery-discharge equations corresponding to the at least one of the series of battery-discharge-current intervals according to the detected discharge current; 
 E. calculating a residual discharging time of the batteries; 
 F. accumulating and recording the discharge time of the at least one of the series of battery-discharge-current intervals corresponding to the selected separate battery-discharge equation; 
 G. judging whether the discharge voltage is lower than a predetermined value, and returning to the step B if the discharge voltage is higher than the predetermined value; 
 H. calculating an estimation error of the residual discharging time when the discharge voltage is lower than the predetermined value; 
 I. judging whether the estimation error is greater than a predetermined error value, and terminating if the estimation error is lower than the predetermined error value; and 
 J. adjusting parameters of the selected separate battery-discharge equation if the estimation error is greater than the predetermined error value. 
 
     
     
       2. The estimation method for the residual discharging time of the batteries as defined in  claim 1 , wherein the multiple separate battery-discharge equations are separate Peukert equations. 
     
     
       3. The estimation method for the residual discharging time of the batteries as defined in  claim 2 , wherein each separate Peukert equation for calculating an initial residual discharging time is
     t   p   =K/I   n    
 where t p  is the initial residual discharging time of the batteries, K and n are parameters of the separate Peukert equation, and I is the discharge current; and 
 wherein an equation for calculating the residual discharging time is
     t   rm   =t   p   −t   sm    
 
 where t rm  is a real-time discharge residual time of the batteries and t sm  is an accumulation of the residual discharging time of the series of battery-discharge-current intervals. 
 
     
     
       4. The estimation method for the residual discharging time of the batteries as defined in  claim 1 , wherein, in the step H: calculating the estimation error of the residual discharging time when the discharge voltage is lower than the predetermined value of the discharge voltage, the estimation error of the residual discharging time equals the calculated residual discharging time. 
     
     
       5. The estimation method for the residual discharging time of the batteries as defined in  claim 3 , wherein, in the step J: adjusting the parameters of the selected separate battery-discharge equation if the estimation error is greater than the predetermined error value, the parameter “K” of the separate Peukert equation is calculated in the form of
     K =( t   p *Error(%)*Φ+ t   p )* I   n   (0≦Φ≦1)
 
 where K and n are the parameters of the separate Peukert equation, t p  is the initial residual discharging time, Error(%) is the estimation error of the residual discharging time, I is the discharge current, and Φ is an adjustment ratio value. 
 
     
     
       6. The estimation method for the residual discharging time of the batteries as defined in  claim 5 , wherein the adjustment ratio value Φ is a product of the discharge time and a mean value of the discharge current within the at least one of the series of battery-discharge-current intervals corresponding to the associated separate Peukert equation, and then the product is divided by the discharge capacity of the batteries, and wherein the mean value of the discharge current is an average of a maximum and a minimum of the discharge current within the at least one of the series of battery-discharge-current intervals corresponding to the selected separate Peukert equation. 
     
     
       7. The estimation method for the residual discharging time of the batteries as defined in  claim 1 , wherein each of the multiple separate battery-discharge equations has a set of different parameters. 
     
     
       8. The estimation method for the residual discharging time of the batteries as defined in  claim 2 , wherein each of the separate Peukert equations has a set of different parameters. 
     
     
       9. The estimation method for the residual discharging time of the batteries as defined in  claim 1 , wherein the series of battery-discharge-current intervals are battery-discharging time intervals suitable for different discharging procedures.